Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen
OPUS4-40424 Wissenschaftlicher Artikel Hahn, Marc Benjamin; Meyer, Susann; Kunte, Hans-Joerg; Solomun, Tihomir; Sturm, Heinz Measurements and simulations of microscopic damage to DNA in water by 30 keV electrons: A general approach applicable to other radiation sources and biological targets The determination of the microscopic dose-damage relationship for DNA in an aqueous environment is of a fundamental interest for dosimetry and applications in radiation therapy and protection. We combine geant4 particle-scattering simulations in water with calculations concerning the movement of biomolecules to obtain the energy deposit in the biologically relevant nanoscopic volume. We juxtaposition these results to the experimentally determined damage to obtain the dose-damage relationship at a molecular level. This approach is tested for an experimentally challenging system concerning the direct irradiation of plasmid DNA (pUC19) in water with electrons as primary particles. Here a microscopic target model for the plasmid DNA based on the relation of lineal energy and radiation quality is used to calculate the effective target volume. It was found that on average fewer than two ionizations within a 7.5-nm radius around the sugar-phosphate backbone are sufficient to cause a single strand break, with a corresponding median lethal energy deposit being E1/2=6±4 eV. The presented method is applicable for ionizing radiation (e.g., γ rays, x rays, and electrons) and a variety of targets, such as DNA, proteins, or cells. USA American Physical Society NaN Physical Review E 95 5 052419-1 052419-8 urn:nbn:de:kobv:b43-404244 10.1103/PhysRevE.95.052419 4 Material und Umwelt
OPUS4-38698 Wissenschaftlicher Artikel Hahn, Marc Benjamin; Meyer, Susann; Schröter, Maria-Astrid; Seitz, H.; Kunte, Hans-Jörg; Solomun, Tihomir; Sturm, Heinz Direct electron irradiation of DNA in fully aqueous environment. Damage determination in combination with Monte Carlo simulations We report on a study in which plasmid DNA in water was irradiated with 30 keV electrons generated by a scanning electron microscope and passed through a 100 nm thick Si3N4 membrane. The corresponding Monte Carlo simulations suggest that the kinetic energy spectrum of the electrons throughout the water is dominated by low energy electrons (<100 eV). The DNA radiation damage, single-strand breaks (SSB) and double-strand breaks (DSB), was determined by electrophoresis. The median lethal dose of D1/2 = 1.7 ± 0.3 Gy was found to be much smaller compared to partially or fully hydrated DNA irradiated under vacuum conditions. The ratio of DSB to SSB was found to be (1:12) as compared to 1:88) found for hydrated DNA. Our method enables quantitative measurements of radiation damage to biomolecules (DNA, proteins) in solutions under varying conditions (pH, salinity, cosolutes) for an electron energy range which is difficult to probe by standard methods. Royal Society of Chemistry 7 Physical Chemistry Chemical Physics 19 3 1798 1805 urn:nbn:de:kobv:b43-386981 10.1039/C6CP07707B 4 Material und Umwelt
OPUS4-42828 Wissenschaftlicher Artikel Schröter, Maria-Astrid; Meyer, Susann; Hahn, Marc Benjamin; Solomun, Tihomir; Sturm, Heinz; Kunte, Hans-Jörg Ectoine protects DNA from damage by ionizing radiation Ectoine plays an important role in protecting biomolecules and entire cells against environmental stressors such as salinity, freezing, drying and high temperatures. Recent studies revealed that ectoine also provides effective protection for human skin cells from damage caused by UV-A radiation. These protective properties make ectoine a valuable compound and it is applied as an active ingredient in numerous pharmaceutical devices and cosmetics. Interestingly, the underlying mechanism resulting in protecting cells from radiation is not yet fully understood. Here we present a study on ectoine and its protective influence on DNA during electron irradiation. Applying gel electrophoresis and atomic force microscopy, we demonstrate for the first time that ectoine prevents DNA strand breaks caused by ionizing electron radiation. The results presented here point to future applications of ectoine for instance in cancer radiation therapy. Nature NaN Scientific Reports 7 1 15272, 1 15272, 7 urn:nbn:de:kobv:b43-428287 10.1038/s41598-017-15512-4 4 Material und Umwelt
OPUS4-35800 Wissenschaftlicher Artikel Hahn, Marc Benjamin; Solomun, Tihomir; Wellhausen, Robert; Herrmann, S; Seitz, H; Meyer, Susann; Kunte, Hans-Jörg; Zeman, J.; Uhlig, F; Smiatek, J; Sturm, Heinz Influence of the Compatible Solute Ectoine on the Local Water Structure: Implications for the Binding of the Protein G5P to DNA Microorganisms accumulate molar concentrations of compatible solutes like ectoine to prevent proteins from denaturation. Direct structural or spectroscopic information on the mechanism and about the hydration shell around ectoine are scarce. We combined surface plasmon resonance (SPR), confocal Raman spectroscopy, molecular dynamics simulations, and density functional theory (DFT) calculations to study the local hydration shell around ectoine and its influence on the binding of a gene-S-protein (G5P) to a single-stranded DNA (dT(25)). Due to the very high hygroscopicity of ectoine, it was possible to analyze the highly stable hydration shell by confocal Raman spectroscopy. Corresponding molecular dynamics simulation results revealed a significant change of the water dielectric constant in the presence of a high molar ectoine concentration as compared to pure water. The SPR data showed that the amount of protein bound to DNA decreases in the presence of ectoine, and hence, the protein-DNA dissociation constant increases in a concentration-dependent manner. Concomitantly, the Raman spectra in terms of the amide I region revealed large changes in the protein secondary structure. Our results indicate that ectoine strongly affects the molecular recognition between the protein and the oligonudeotide, which has important consequences for osmotic regulation mechanisms. 8 The journal of physical chemistry / B 119 49 15212 15220 10.1021/acs.jpcb.5b09506 4 Material und Umwelt
OPUS4-41164 Konferenzveröffentlichung Hahn, Marc Benjamin; Solomun, Tihomir; Meyer, Susann; Kunte, Hans-Joerg; Schröter, Maria-Astrid; Sturm, Heinz Development of a standard procedure for the irradiation of biomolecules In dosimetry the determination of the effectiveness of the damaging processes is standardized and accounted for by the radiation and tissue weighting factor. For the underlying constituents of the tissue, that is the various biomolecules, such a systematic approach doesn't exist. This makes it difficult to compare results obtained under different experimental conditions. In the following work, we will describe a method to obtain comparable values for the radiation-biomolecule interaction, measured under different conditions. This approach can lead to standardization of dosedamage relationship at the molecular level. Such approach is necessary for a better understanding of the relations between the damage of the single constituents of biological tissue and the whole - finally gaining a more complete picture of irradiation damage. 4 Proceedings of the 14th IRPA International Congress 14 1 5 6 Materialchemie